The present invention relates in general to storage container sealing caps, and in particular to an improved sealing cap for safety storage containers incorporating automatic vacuum relief venting.
Containers designed and intended for the safe storage, handling and dispensing of fluids, particularly volatile or corrosive fluids, must provide many functions. A typical storage container for use in connection with such fluids may provide separate openings for filling and for dispensing, such as a first large accessible opening for easy and safe filling and a second smaller controlled opening for safe dispensing. Typical configurations include Type II safety dispensing cans which may include a flexible hose outlet for controlled and directed delivery of volatile or corrosive fluids, and laboratory shelf or tilt cans with top or bottom mounted dispensing valves.
Satisfactory operation of such dispensing cans requires that provision be made for admitting air into the interior of the can in order to replace the fluid contents as they are removed by pouring or otherwise and thereby maintain an equal pressure between the interior of the container and the ambient atmosphere exterior to the container. Failure to provide such pressure equalization may result in a rising vacuum within the container and an influx of air through the dispensing hose or valve, interrupting the fluid flow and causing uncontrolled splashing and surges of dispensed fluid. Collapse of the container may also occur.
In order to avoid such conditions, separate air vent openings between the interior of the container and the exterior of the container may be provided. For example, it is known to provide for a small separate opening with a manually sealable cap, such as a flip-top vent opening. The operator must open this auxiliary vent prior to dispensing, and must then reseal the opening to provide for safe storage and transportation. Other forms of manual venting are also known.
In order to avoid such manual vent operation, it is known to provide a vent which is operated by the same activating means used to control the dispensing outlet or valve. For example, an operating trigger which controls a fluid dispensing valve may simultaneously operate a second vent valve positioned to admit air to the interior of the container. Such arrangements provide increased safety and security by assuring that the vent opening or valve is closed when the fluid is not being dispensed, such as during storage. The necessity for providing a mechanical linkage and a separate vent opening through the container, however, add to the complexity and cost of the resulting storage container.
It is further desirable to provide such storage containers with means for automatically equalizing the interior and exterior pressure in response to an interior vacuum created by the contraction of the container contents, or by increases in the exterior ambient pressure. Failure to provide such automatic relief may result in a partial collapse of the container. Such operation is generally not provided by the manual vent discussed, or by the dispensing trigger operated vent.
In order to provide for an improved and economical safety storage container, it is therefore desirable to provide a system which may simultaneously provide the sealing and venting functions described, without requiring specialized containers or mechanical linkages. Accordingly, it is an object of the present invention to provide a sealing cap for a fill opening of a fluid storage container which provides for automatic relief of an interior partial vacuum when the fluid contents of the container are dispensed through a second dispensing opening. A related object is to provide for automatic relief of an internal partial vacuum in the container without the need for manual operation or mechanical linkage to a dispensing trigger mechanism.
A further object is to provide for adequate venting of internal partial vacuum without requiring a specialized or additional vent opening in the associated container.
A further object is to provide an integrated sealing cap and partial vacuum venting system for use in conjunction with standard safety storage containers. A specific object is to provide such an automatic venting cap for use in conjunction with standard metal or plastic Type I and type II safety storage containers, including the common "jerry" can. Yet a further specific object is to provide such an integrated sealing and venting cap in conjunction with a laboratory dispensing can, designed either for shelf use with a bottom mounted dispensing valve, or for tilt stand use with a second top dispensing valve.
A further object is to provide such a partial vacuum venting valve assembly which is particularly immune to the effects of corrosive fluids in the storage container.
Another object is to provide such an integrated venting and sealing cap which is designed to use with existing sealing cap mounting apparatus.
These and other objects of the present invention will become apparent in light of the following specifications.